Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B13/00—Machines or devices designed for grinding or polishing optical surfaces on lenses or surfaces of similar shape on other work; Accessories therefor
  • B24B13/005—Blocking means, chucks or the like; Alignment devices
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
  • B23Q1/00—Members which are comprised in the general build-up of a form of machine, particularly relatively large fixed members
  • B23Q1/25—Movable or adjustable work or tool supports
  • B23Q1/26—Movable or adjustable work or tool supports characterised by constructional features relating to the co-operation of relatively movable members; Means for preventing relative movement of such members
  • B23Q1/40—Movable or adjustable work or tool supports characterised by constructional features relating to the co-operation of relatively movable members; Means for preventing relative movement of such members using ball, roller or wheel arrangements
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S156/00—Adhesive bonding and miscellaneous chemical manufacture
  • Y10S156/934—Apparatus having delaminating means adapted for delaminating a specified article
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T156/00—Adhesive bonding and miscellaneous chemical manufacture
  • Y10T156/19—Delaminating means
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49815—Disassembling
  • Y10T29/49819—Disassembling with conveying of work or disassembled work part
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49815—Disassembling
  • Y10T29/49822—Disassembling by applying force
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49826—Assembling or joining
  • Y10T29/49895—Associating parts by use of aligning means [e.g., use of a drift pin or a "fixture"]
  • Y10T29/49902—Associating parts by use of aligning means [e.g., use of a drift pin or a "fixture"] by manipulating aligning means
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/49998—Work holding

Definitions

• This invention relates to the manufacture of lenses, especially contact lenses.
• Contact lenses are conventionally manufactured by machining suitably sized lens blanks on automatic or semi-automatic lathes. Although according to some machining procedures the lens blank itself is received into the collet of the lathe the more commonly adopted methods involve attaching the lens blank to a chuck which is then received in the lathe collet. After the first curved lens surface has been cut on the blank it is necessary to remove the partly machined blank from- the chuck and to then attach it to the second chuck (known in the contact lens art as a "block”) so that the opposite lens surface can be formed. This procedure of mounting a partly machined lens blank on a block is known in the art as "blocking".
• One difficulty in carrying out the blocking operation is to ensure that the optical axis of the partly machined blank is aligned with the axis of the block so that the second lens surface will be cut on the same axis as the first.
• This procedure is conventionally carried out by manually aligning the blocks and the lens blank and is accordingly an extremely laborious and skilled operation. Failure to achieve accurate alignment of the lens blank and block will lead to the rejection of the lens in final checking owing to poor edge control or prism.
• a method of mounting a partly formed lens blank, having a first lens surface, on a block in order to be able to cut a second lens surface on the blank said method comprising bringing the block into contact with the first lens surface of the partly formed, e.g.
• the block is conveniently lowered onto a blank, which is supported so that its optical axis is maintained in a vertical disposition, while being free to move to a limited extent in a horizontal plane. If the partly machined lens blank has been machined to form the first lens surface while supported on a chuck, the blank may be transferred directly from its associated chuck to a block.
• a blocking machine for. centring a partly machined lens blankhaving a first lens surface to a block in order to machine the opposite lens surface, said machine comprising a holder for supporting one of the components comprising the block and lens blank above a moveable table for supporting the other component, said table in at least one mode, being free to move in any direction in a horizontal plane and means for moving the holder and table towards each other and bringing the first lens surface and block into mutual contact.
• the lens blank is attached to a chuck and the lens blank and chuck supported by the table, while the block is mounted in the holder and lowered under the weight of the holder and block onto the lens blank.
• the table on which the lens blank and chuck is supported is arranged to be freely moveable in a horizontal plane and this can be achieved by supporting the table on ball- bearings.
• the table includes means for selectively locking and unlocking the table so that after the transfer operation, the table can be held solidly.
• the blocking machine is Preferably designed to be loaded and unloaded automatically.
• the apparatus may include means for automatically applying adhesive to the block and means for breaking the bond between the chuck and the lens after the blank has been bonded to the block.
• Figure 1 is a side elevation of the blocking apparatus showing the block in a position in which the block has almost been lowered to contact the lens blank.
• Figure 2 is a view taken in the direction of the arrow A in Figure 1,
• Figure 3 is a view taken on the line B-B in Figure 1 but showing in addition clamping means for selectively locking the table.
• Figure 4 is a side elevation of a chuck with a partly machined lens blank adhered to it
• Figure 5 is a side elevation of a block after the partly machined blank has been transferred to it
• Figure 6 is a schematic view of the blocking apparatus incorporated in an automatic machine.
• the blocking apparatus comprises a carriage 1 for supporting a block 2 vertically above a table 3.
• Carriage 1 is guided on a slide 4 and may be raised or lowered on the slide 4 manually or by automatic means, such as by a wheel 5 arranged to run on a cam surface (not shown).
• Carriage 1 comprises a V-shaped block 6 and a pair of rollers 8 carried on arms 9 for supporting the block 2.
• Table 3 comprises an upper part 10 which is supported on a base 11 by means of a bed of ball-bearings 12 (only some of which are shown in Figures 1 and 3) which allow a limited degree of horizontal sliding movement between the upper part 10 and the base 11.
• the upper part 10 of table 3 includes a fork portion 13 for receiving the chuck 14 and its associated lens blank 15 (for clarity the chuck and lens blank are not shown in Figure 3).
• the upper part 10 of lOthe table' has a depending skirt 21 which surrounds the major portion of the base part 11.
• the base part 11 is generally U-shaped when viewed in plan (see Figure 3) so as to accommodate the body of chuck 14.
• Ball bearings 12 are located on base 5part 11 in groups on each side of recess 22 for receiving the body of chuck 14.
• Upwardly projecting walls 23 are provided to retain the balls in beds on each side of recess 22. The upstanding walls 23 trap the balls 12 in the space between the mutually slideable parts of the 0table 3 but without restricting their rolling movement.
• skirt 21 of the upper part 10 limits the extent of mutual horizontal movement of the components of the table, although the upper part 10 is free to move in any direction in a horizontal plane.
• the forked portion 13 is open towards the left hand side of the apparatus as shown in Figure 1 and supports the chuck on the under face of the lens blank 15, the adherent chuck hanging from the forked portion 13.
• the surface 17 is accurately cut at right angles to the axis 17b of the base curve 16.
• the lens blank 15 adjusts and centralises its position relative to the block 2 so that the axis of the latter lies accurately along the axis on which the base curve 16 had been cut.
• the molten adhesive between the block 2 and the surface 16 acts as a lubricant during this centralising movement.
• the block and lens blank should be brought together in such a way that a thin, uniform film of molten adhesive exists between the contacting surfaces while the centralising action takes place and before the adhesive cools to form a bond.
• the block should not be at a temperature which is so high as to damage the surface of the lens surface.
• a suitable temperature for the block is about 90°C, just above the melting point of the adhesive, although the optimum temperature depends on the particular adhesive selected and the nature of the lens polymer. It is currently preferred to bring the block fairly rapidly into contact with the lens blank, by allowing the carriage to run down on a steep cam surface under its own weight.
• the blocking machine may be part of an automatic apparatus which is fed sequentially with blocks and with chucks having adherent lens blanks and the resulting blocks and transferred blanks are unloaded subsequently.
• Such automatic apparatus may be incorporated in a lens manufacturing procedure as described in our British patent application No. 8313161 (publication No. 2123733) and it may utilise loading and unloading devices- similar to those described ° in our above application.
• a ⁇ clamping arm 25 Pivotally mounted on a shaft 24 is a ⁇ clamping arm 25, the shaft 24 being 5 journalled in trunnion blocks 27 secured to base plate 26. Attached to the skirt 21 of upper part 10 of table 3, is a horizontally outwardly projecting web 28. Pivotal movement of clamping arm 25 towards the base plate 26 presses down on the web 28 and holds the upper part 10 0 of table 3 rigidly. A spring-biassed latch 29 locks the clamping arm in the clamped position.
• FIG. 1 is a schematic plan view of such an automatic blocking apparatus which consists of a pair of carousels 101 and 102 rotatable in the direction of the arrows. Each carousel has a number of stations at which the operations to be described are carried out and means are provided to rotate the carousels in timed sequence from one station to the next. Blocks 2 (as shown in
• 102 incorporates a heater so that by the time the blocks lOhave reached station 105 their temperature is higher than the melting point of a waxy thermoplastic adhesive. This is applied at station 105 by lifting a bath of molten adhesive into contact "with the rounded end of the block.
• Devices 110 are wedges which are arranged to lock the carousels after each indexing step.
• Carriage 1 moves down on slide 4 under the control of the wheel 5 sliding on a cam surface and the table 3 at this point is unlocked 0so that the upper part 10 is floating on the bearings 12.
• the rounded tip of the block is lowered onto the surface
• the block hangs vertically in the Vee-block 6 and with the table 3 free to move in a horizontal plane, 5 the block is centralised and aligned with respect to the lens blank.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Grinding And Polishing Of Tertiary Curved Surfaces And Surfaces With Complex Shapes (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=10559933

Family Applications (1)

Country Status (6)

Cited By (1)

Families Citing this family (14)

Citations (6)

Family Cites Families (14)

• 1984
  • 1984-04-19 GB GB848410341A patent/GB8410341D0/en active Pending
• 1985
  • 1985-04-18 GB GB08509993A patent/GB2157598B/en not_active Expired
  • 1985-04-18 DE DE8585902072T patent/DE3563705D1/de not_active Expired
  • 1985-04-18 JP JP60501755A patent/JPS61501902A/ja active Granted
  • 1985-04-18 EP EP85902072A patent/EP0179116B1/en not_active Expired
  • 1985-04-18 WO PCT/GB1985/000170 patent/WO1985004829A1/en active IP Right Grant
  • 1985-04-18 US US06/816,120 patent/US4677729A/en not_active Expired - Fee Related
• 1987
  • 1987-04-20 US US07/043,475 patent/US4759154A/en not_active Expired - Fee Related

Patent Citations (6)

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